The Middle East Respiratory Syndrome—How Worried Should We Be?

Perlman, Stanley

Transmission appears to occur more readily if the recipient is immunocompromised or has another comorbidity, such as diabetes. In the largest outbreak described thus far, 23 patients with laboratory-confirmed infection were followed in Al-Ahsa governorate in Saudi Arabia (3) . Diabetes mellitus (74%), end-stage renal disease (52%), and lung disease (43%) were underlying illnesses in these patients. Transmission to family members and health care workers was documented in 1 to 2% of contacts, again demonstrating preferential infection of individuals with substantial comorbidities. Unlike another human respiratory coronavirus, the one that caused the severe acute respiratory syndrome (SARS) in 2002-2003, MERS-CoV has not preferentially infected health care workers. At present, it is not known if patients are able to transmit virus before the development of symptomatic respiratory disease. If this does occur, control of a large outbreak will be more difficult. The SARS epidemic was contained, in part, because the majority of patients were infectious only after they developed pneumonia.